Prevent my clients from giving or selling my software using a LGPLv3 library to others

Question

I am developing a commercial closed software using Qt which is under LGPLv3.

May I prevent my clients from giving copies to other people?

Answer 1

If it were a GPL app, you wouldn't be able to do this, but LGPL has an important difference: the viral licensing property doesn't affect your project's code if you dynamically link to it. So as long as all the QT code is in its own DLLs, rather than compiled directly into your project, you'll be fine.